Using a "railgun launcher" or a long-travel solenoid

[Knufire]

For electric solenoids, R29 (the list of allowed motors and actuators) states:

Electrical solenoid actuators, no greater than 1 in. stroke and rated electrical input power no greater than 10 watts (W) continuous duty at 12 volts (VDC) - Unlimited

For custom circuits, R40 states:

Any active electrical item not explicitly listed in R29 or R67 is considered a CUSTOM CIRCUIT. CUSTOM CIRCUITS may not produce voltages exceeding 24V when referenced to the negative terminal of the battery.